Geologic units in Langlade county, Wisconsin

Wolf River batholith; Wolf River Granite (Middle Proterozoic) at surface, covers 29 % of this area

Red, coarse-grained rapakivi granite consisting of large (1-3 cm) ovoid alkali feldspar sporadically mantled by plagioclase, interstitial plagioclase, quartz, biotite, hornblende, and ilmenite

Mafic metavolcanic rocks (Early Proterozoic) at surface, covers 24 % of this area

Dominantly tholeiitic basalt and basaltic andesite flows and tuffs; associated with sheet dikes, massive and layered metagabbro, and ultramafic rocks. In northeastern Wisconsin, rocks have been named the Quinnesec Formation.

Mafic to felsic metavolcanic rocks (Early Proterozoic) at surface, covers 23 % of this area

Volcanic rocks in areas of sparse geologic data and nondefinitive magnetic and gravity data

Wolf River Batholith; Anorthosite (Middle Proterozoic) at surface, covers 9 % of this area

Gray, coarse-grained (1-20 cm) plagioclase-rich (An45-53) rock containing interstitial orthopyroxene, clinopyroxene, Fe-Ti oxides, and apatite.

Wolf River batholith; Hager Formation; Rhyolite member (Middle Proterozoic) at surface, covers 8 % of this area

Gray to reddish-gray, slightly foliated, porphyritic rhyolite containing aligned phenocrysts of alkali feldspar and lesser amounts of plagioclase in a fine-grained matrix of feldspar, biotite, amphibole, and sparse quartz

Porphyritic granite (Early Proterozoic) at surface, covers 2 % of this area

Granite containing plagioclase, microcline, and quartz phenocrysts in a fine-grained granophyric matrix. Probably subvolcanic intrusions related to volcanic rocks of 1835- to 1845-Ma age group

Felsic metavolcanic rocks of 1835- to 1845-Ma age group (Early Proterozoic) at surface, covers 2 % of this area

Rhyolite to dacite and, locally, andesite tuff, breccia, and minor sedimentary rocks, including conglomerate. Exposed in central Wisconsin.

Granitic rocks of 1760-Ma age group (Early Proterozoic) at surface, covers 1.0 % of this area

In northern Wisconsin, granite to granodiorite of varied texture. In southern Wisconsin (not mapped separately), red to pink alkali-feldspar granophyric granite associated with rhyolites of both peraluminous and metaluminous affinities (unit Xr of Marshfield terrane).

Quartzite (Early Proterozoic) at surface, covers 0.7 % of this area

Maroon but locally white, gray, and red quartzite (quartz arenite) with a basal quartzose conglomerate. At Flambeau Ridge (Chippewa County) consists of conglomerate. Distinguished from other quartzite units in being strongly deformed and metamorphosed. Includes Flambeau, Rib Mountain, McCaslin, and Thunder Mountain Quartzites of local usage

Granodiorite-tonalite (Early Proterozoic) at surface, covers < 0.1 % of this area

Gray, medium-grained intrusive rocks, including intrusion breccias. Exposed in central Wisconsin. Zircon ages range from 1837 to 1847 Ma